The present invention relates to corrosion inhibitor compositions. More specifically, it relates to corrosion inhibitor compositions for use with high density brines.
In many wells, e.g., oil, gas, etc., it may be desirable to contain the formation pressure by employing a hydrostatic head. This may be needed during the squeezing of sand consolidation compositions, during perforation operations, during well shut-ins, during gravel packing, or the like. Many well-servicing fluids, sometimes referred to as completion or packer fluids, have been employed. These include, for example, drilling muds, salt water, brines, water, oil, ZnCl.sub.2 -CaCl.sub.2 solutions, CaCl.sub.2 -CaBr.sub.2 solutions and the like.
In recent years, deeper, high-pressure wells have resulted in a need for solids-free, well-servicing fluids having higher densities than are currently available. This is particularly true of wells in the Gulf of Mexico (offshore Louisiana), where higher hydrostatic pressures often require well-servicing fluids having densities in excess of 15 pounds per gallon (ppg). The need for solids-free, higher density well-servicing fluids is met by brines which contain zinc salts, such as zinc halides. These zinc-containing brines have the disadvantage of being more corrosive than brines which are substantially free of zinc salts. Therefore, the high density brines, i.e., those brines having densities greater than about 14.5 ppg, are especially corrosive to oil well casings and equipment used in the service of said casings. The corrosion problem is exacerbated by the higher temperatures typically found in the deeper wells in which high density brines are used. Known corrosion inhibitors, such as film-forming amines, which have been used in high density brines do not provide adequate protection from corrosion at the higher temperatures associated with the deep wells in which high density brines typically are employed. Therefore, it would be desirable to develop a corrosion inhibiting agent which provides increased protection for metals from corrosion caused by high density brines, especially by zinc-salt-containing high density brines at the higher temperatures found in deep wells.